The airline has admitted that the industrial action was costing the airline £7 million a day. Unite estimates the total cost to BA as £119 million.

The impact of the dispute was revealed this week when the airline announced a 14.2% dip in passenger numbers last month. BA carried a total of 2.37 million passengers in May, down from 2.76 million the year before.

A spokesman for BA said the airline expected to increase the number of flights operating during the industrial action as a growing number of strikers return to work.

He said that it intends to operate all flights to South Africa ahead of the World Cup and that 80 per cent of its long haul flights from Heathrow will operate next week.

Short haul services from Heathrow will also be reduced, with 60% flying. During the last five day stoppage 55% of short haul services from the airport operated.

Flights from Gatwick and London City airports will continue to be unaffected.

The spokesman said: "We have announced that we are planning to fly about 80% of our long-haul programme, including all JFK (New York) services and also all South African flights as we approach the World Cup."

Unite is planning to hold another ballot of its cabin crew members, which it has to under employment law, and has warned of a summer of disruption unless there is a deal.

Talks between Unite's joint leader Tony Woodley and BA's chief executive Willie Walsh under the auspices of the conciliation service Acas ended without agreement last week, with little sign of any progress.

An agreement in principle has been struck over cost-cutting, the original cause of the dispute, but the removal of travel concessions from strikers is now blocking a deal.

Unite has urged BA to fully restore the travel concessions, arguing it would not cost the airline any money.

The union said it believed the next series of strikes will be strongly supported by cabin crew and will have a "huge impact" on flights.

Singer Billy Bragg will perform an impromptu gig for the strikers at a football ground near Heathrow on Saturday.

Unite will increase strike pay, currently £30 a day, for the next five-day walkout, in recognition of the financial hardship the workers are facing.